Metal ion modified high surface area materials for odor removal and control

ABSTRACT

This invention relates to high surface area materials, such as nanoparticles, that are coated with metal ions. These modified nanoparticles have active sites that bind various gases and/or odorous compounds, thereby removing these compounds from a medium such as air or water. Metal ions are adsorbed onto the surface of the nanoparticle and bound strongly to the surface. By selection of the metal ion, specific gaseous compounds and/or odorous compounds can be targeted and removed efficiently and effectively from both aqueous phase and from the air. The modified nanoparticles are useful in numerous article of manufacture for industrial and consumer use.

RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.12/546,755, filed on Aug. 25, 2009 which is a divisional of U.S.application Ser. No. 10/137,052 filed on Apr. 30, 2002, now U.S. Pat.No. 7,578,997, which is incorporated herein in its entirety by referencethereto.

FIELD OF THE INVENTION

This invention relates to modified high surface area materials useful inneutralizing or removing gases and/or odorous compounds. The highsurface area material, such as a nanoparticle, is coated with metal ionsthat can bind with gas molecules and/or odorous compounds. The modifiedhigh surface area materials can be incorporated into various industrialand consumer products including absorbent articles, air and waterfilters, household cleaners, fabrics, and paper towels.

BACKGROUND OF THE INVENTION

Many attempts have been made to formulate an effective odor removalsystem and various consumers products are available for combatingodorous compounds. Some products are designed to cover up odors byemitting stronger, more dominant odors, examples including scented airfreshener sprays and candles. Another way to combat odorous compounds,including ammonia, methyl mercaptan, trimethylamine, and other varioussulfides and amines, is to remove these compounds from a medium bydeodorizing agents that will absorb these compounds.

Activated charcoal and sodium bicarbonate are two compounds commonlyused to absorb odors. However, activated charcoal typically has a lowdeodorizing ability, especially for ammonia odors and when in thepresence of moisture, and the black color of charcoal lacksaesthetically pleasing characteristics desired in absorbent articlessuch as diapers. Sodium bicarbonate, and other white odor absorbentssuch as silica gel and zeolites, generally have a lower absorbency thanactivated charcoal and are therefore less effective.

Titanium oxide particle, such as taught in U.S. Pat. No. 5,480,636issued to Maruo et al., are also useful in removing a few odors such asammonia. U.S. Pat. No. 5,480,636 teaches adding zinc oxy or silicon oxycompounds to the titanium oxide to broaden the titanium oxidedeodorizing capabilities. However, this approach is still limited by thephotocatalytic nature of the titanium dioxide which requires light inorder to convert odorous compounds into non-odorous compounds. Also thetitanium oxide compounds as disclosed in U.S. Pat. No. 5,480,636 are notuseable in aqueous solutions.

In addition to foul smelling compounds, there is a need for productscapable of removing gases that, while not necessarily odorous, stillcause a negative effect. One example of such a gaseous compound isethylene. Ethylene, a natural hormone, is released by fruits as aripening agent. By removing ethylene gas, fruit ripening could be slowedand controlled, allowing for extended storage and transportation.

There is a need for a gas and/or odor removal/neutralizing compound thatis effective both dry and in solution. There is a need for an effectiveodor removal/neutralizing compound that can be used in variousindustrial and consumer products. There is a need for a gas and/or odorremoval/neutralizing compound that can be easily applied to varioussurfaces and materials.

SUMMARY OF THE INVENTION

This invention relates to high surface area materials that are coatedwith metal ions. These modified high surface area materials have activesites that bind at least one gaseous compound and/or odorous compound,thereby removing these compounds from a medium such as air or water.Nanoparticles are a type of high surface area materials useful in thisinvention to remove at least one of gaseous compounds and odorouscompounds. At least one type of metal ion is adsorbed onto the surfaceof the nanoparticle and bound strongly to the surface. By selection ofthe metal ion, certain gaseous compounds and/or odorous compounds can betargeted and removed efficiently and effectively from both aqueous phaseand from the air. This invention uses high surface area nanoparticles astemplates to adsorb specific functionalities (metal ions) that target atleast one of gaseous compounds and odorous compounds and form complexeswith them and remove them from the media. For example, silicananoparticles modified by copper ions (or alternatively, silver ions)were demonstrated to be effective in removing amine and sulfur basedclasses of odorous compounds.

It is one object of this invention to create an effective gaseouscompound removal system. The invention is useful in various industrialand consumer products. It is another object of this invention to createa gaseous compound removal system for inhibiting the ripening of plantmaterials.

It is another object of this invention to create an effective odorremoval compound useful in both aqueous phase and in the air. It isanother object of this invention to create an effective odor removalcompound that can effectively be used in various industrial and consumerproducts. This invention can be used in combination with variousproducts for the removal of odors. Modified high surface area materialsof this invention are useful in absorbent articles such as diapers andfeminine products for removing odors. Modified high surface areamaterials of this invention are useful in filtration devices and coatedonto walls, wall paper, and glass for removal of odors. Modified highsurface area materials of this invention are useful in oral careproducts such as mouthwash and chewing gum for the removal of compoundsin the mouth that cause unpleasant odors.

The foregoing and other features and advantages will become furtherapparent from the following detailed description of the presentlypreferred embodiments read in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing of a modified nanoparticle according to oneembodiment of this invention.

FIG. 2A is a high performance liquid chromatography chromatogram.

FIG. 2B is a high performance liquid chromatography chromatogram.

FIG. 3A is a high performance liquid chromatography chromatogram.

FIG. 3B is a high performance liquid chromatography chromatogram.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

This invention relates to high surface area materials, such asnanoparticles, modified with at least one metal ion. The modified highsurface area materials of this invention are useful in removing gaseouscompounds and/or odorous compounds. “Gaseous compound” or “gas” includesany molecule or compound that can exist as a gas or vapor. “Odorouscompound” or “odor” refers to any molecule or compound detectable to theolfactory system. Odorous compounds can exist as a gaseous compound andcan also be present in other media such as liquid.

The high surface area materials of this invention have at least onemetal ion present on the surface of the high surface area material, andthe metal ion creates an active site that binds with at least onegaseous compound and/or odorous compound thereby removing the compoundfrom the surrounding environment. High surface area materials can alsoabsorb certain gaseous compounds and/or odorous compounds from thesurrounding environment by adsorption directly onto the surface area ofthe high surface area materials.

Gas and/or odor removing particles of this invention are modified highsurface area materials. High surface area materials useful in thisinvention have a large surface area due to the small size of theindividual particles of the high surface area material. High surfacearea materials useful in this invention have a suitable surface area ofat least about 200 square meters/gram, more suitably 500 squaremeters/gram, and more suitably 800 square meters/gram.

Nanoparticles are examples of high surface area materials useful in thisinvention. “Nanoparticle” refers to a high surface material having aparticle diameter of less than about 500 nanometers. While the inventionwill be described hereinafter with particular reference tonanoparticles, it will be understood that the invention is useful withvarious high surface area materials. FIG. 1 shows a modified ananoparticle 10 according to one embodiment of this invention, useful asa gas and/or odor removing particle. The modified nanoparticle 10includes a nanoparticle 15 and metal ions 20. FIG. 1 shows a pluralityof metal ions 20, however modified nanoparticle 10 can have variousamounts of metal ions 20 and will have at least one metal ion 20. Themodified nanoparticle 10 is useful for removing various gaseouscompounds and/or odorous compounds. The specific compound to be removedis generally dependent on the specific metal ions 20 used and the typeof nanoparticle 15.

Nanoparticles useful in this invention include, without limitation,silica, alumina, magnesium oxide, titanium dioxide, iron oxide, gold,zinc oxide, copper oxide, organic nanoparticles such as polystyrene, andcombinations thereof. Nanoparticles are not generally ionic yet stillhave an overall electric Zeta Potential. “Zeta Potential” refers to theelectrical potential, or electrokinetic potential, that exists acrossthe interface of all solids and liquids. Nanoparticles with eitherpositive or negative Zeta Potentials are known. Naturally occurringchemical reactions on the surface of a nanoparticle result in the ZetaPotential of that nanoparticle. For example, silica nanoparticles aretetrahedral complexes of silicon dioxide molecules. On the surface ofthe silica particles the silicon dioxide molecules can undergo chemicalreactions forming silanol groups (SiOH) the silanol groups reacting withother silanol groups to form siloxane bonds (Si—O—Si bonds). Thedehydration reactions of the silanol groups to form the silanol bond andthe reverse reactions result in a negative Zeta Potential and allowpositively charged metal ions to adsorb onto the silica.

The nanoparticles useful in this invention will typically have a firstZeta Potential and a second Zeta Potential after adsorption of the metalion onto the nanoparticle due to the addition of the oppositely-chargedmetal ions. The Zeta Potential change of the nanoparticle is related tothe amount of metal ions adsorbed onto the nanoparticle. Thisrelationship provides a measurement for determining the amount ofadsorbed metal ions and a method for controlling the amount ofadsorption. For instance, the addition of a dilute solution of copperchloride drop-wise to a silica nanoparticle solution until the ZetaPotential of the silica suspension changed from −25 millivolts to ahigher Zeta Potential, such as in the range of about −5 millivolts to−15 millivolts, was found to be provide a sufficient concentration ofmetal ions adsorbed onto the nanoparticles to remove particular odorouscompounds. In one embodiment of this invention the nanoparticle has adifference between the first and second Zeta Potential of at least about1.0 millivolt and suitably at least about 5.0 millivolts.

The nanoparticles of this invention are modified with metal ions thationically bond with compounds such as gases and odorous compounds.“Metal ion” refers to salt ions and/or ion complexes of transition metalelements designated as IB through VIIIB on the periodic table. Otherions can be used in the invention as well. Metal ions are adsorbed ontohigh surface area materials due to differences in electric potential.Positively charged metal ions are adsorbed onto a negatively chargedsurface of a nanoparticle and vice versa. Examples of metal ions usefulin this invention include, without limitation, copper ion (Cu⁺²), silverion (Ag⁺¹), gold ion (Au⁺¹ and Au⁺³), iron (II) ion (Fe⁺²), iron (III)ion (Fe⁺³), permanganate ion (MnO₄ ⁻¹), and combinations thereof.

In one embodiment of this invention the nanoparticle useful in thisinvention has a negative Zeta Potential and adsorbs positively chargedmetal ions. One suitable nanoparticle has a negative Zeta Potential ofabout −1 to −50 millivolts and suitably about −1 to −20 millivolts. Inone embodiment of this invention the nanoparticle having a negative ZetaPotential is a silica nanoparticle. Silica nanoparticles useful in thisinvention are available from Nissan Chemical Industries, Ltd., Houston,Tex., under the name SNOWTEX®, have a particle size range of 1-100nanometers. The silica nanoparticle can be modified with a positivelycharged metal ion such as copper ions, silver ions, gold ions, ironions, and combinations thereof.

In another embodiment of this invention the nanoparticle useful in thisinvention has a positive Zeta Potential and adsorbs negatively chargedmetal ion complexes. One suitable nanoparticle has a positive first ZetaPotential of about 1 to 70 millivolts and suitably about 10 to 40millivolts. In one embodiment of this invention the nanoparticle havinga positive Zeta Potential is an alumina nanoparticle. Aluminananoparticles are also available from Nissan Chemical Industries, Ltd.,Houston, Tex., under the name ALUMINASOL®, and have size ranges of about1-300 nanometers. The alumina nanoparticle can adsorb negatively chargedmetal ions and metal ion complexes such as permanganate ions.

Current odor control materials such as activated charcoal or sodiumbicarbonate rely on the surface area to absorb certain odors. Usingthese materials is not as effective at odor removal than the modifiedhigh surface area materials of this invention. The addition of a metalion adsorbed onto the surface of a nanoparticle, as in this invention,provides an active site for capturing and neutralizing gases and odorouscompounds. In addition, the modified nanoparticles of this inventionstill have the large surface area that is useful in absorbing otherodorous compounds. The metal ion active sites of the modifiednanoparticles are particularly useful in removing odorous compound suchas mercaptans, ammonia, amines, and mono- and di-sulfides. Other odorouscompounds such as aliphatic ketones, carboxylic acids, aliphaticaldehydes, and aliphatic terpenoids can be removed by adsorption ontothe large surface area of the modified nanoparticles. Modifiednanoparticles are useful in removing odors caused by sulfides,disulfides, trisulfides, thiols, mercaptans, ammonia, amines, isovalericacid, acetic acid, propionic acid, hexanal, heptanal, 2-butanone,2-pentanone, 4-heptanone, and combinations thereof. Modifiednanoparticles can also remove gases such as ethylene gas, carvone,dienals, and terpenoids.

More than one type of metal ion can be coated on a nanoparticle. Thishas an advantage in that certain metal ions may be better at removingspecific gases and/or odorous compounds than other metal ions. In oneembodiment of this invention more than one type of metal ion areadsorbed onto a nanoparticle for more effectively removing more than onetype of gaseous compound or odorous compound from a medium. In oneembodiment of this invention more than one type of metal ion areadsorbed onto a nanoparticle for removing at least one gaseous compoundand at least one odorous compound from a medium.

Modified nanoparticles of this invention can be used in combination withother modified nanoparticles for effective removal of various gases andodors. In one embodiment of this invention copper ion modified silicananoparticles are used in combination with permanganate ion modifiedmagnesium oxide nanoparticles. By using the two different modifiednanoparticles in combination, numerous odorous compounds can be removed.For example, the modified silica nanoparticle is useful for removingsulphur and amine odors and the modified magnesium oxide nanoparticle isuseful in removing carboxylic acid odors. Combining modifiednanoparticles of this invention allow for removal of a broader range ofodors.

Modified nanoparticles are made by mixing nanoparticles with solutionscontaining metal ions. Such solutions are generally made by dissolvingmetallic compounds into a solvent resulting in free metal ions in thesolution. The metal ions are drawn to and adsorbed onto thenanoparticles due to the electric potential differences. The ZetaPotential of a nanoparticle changes after the adsorption of metal ionsaccording to this invention. Thus the Zeta Potential can be used tomonitor the adsorption of metal ions onto the nanoparticle.

Modified high surface area materials according to this invention areversatile and can be used alone or in combination with other articles ofmanufacture for effective odor removal and control. Unlike activatedcharcoal deodorants, the modified nanoparticles of this inventionmaintain their odor neutralizing effects in solution. The modifiednanoparticles of this invention also maintain odor neutralizingproperties when dry and in aerosol form. This versatility allows foruses in various commercial products. Other advantages of the modifiednanoparticles are that they are colorless in solution and white inpowder form (activated charcoal is typically black). Modified highsurface area materials of this invention can also be used in combinationwith other commercially available odor removal materials.

Modified nanoparticles of this invention can be applied to variousmaterials. In one embodiment of this invention modified nanoparticlesare held onto a surface of a material by the electrical potentialdifferences between the modified nanoparticle (Zeta Potential) and thematerial surface (Streaming Potential).

Modified nanoparticles of this invention can be applied as a solution toa surface and dried resulting in a surface that absorbs gas and/orodors. In one embodiment of this invention the modified nanoparticlesare used in air filters, such as house filters, vent filters, disposableface masks, and face mask filters. In another embodiment the modifiednanoparticles can be applied to walls, wallpaper, glass, toilets, and/orcountertops. For instance, the modified nanoparticles can be used in arestroom facility. Other uses include without limitation refrigeratormats and fabric softener sheets.

In one embodiment of this invention the modified nanoparticle is coatedonto a fibrous cloth. Various types of fibrous cloths are useful in thisinvention including, without limitation, cloth made from natural fiberssuch as wood pulp fibers, cotton fibers, and other plant fibers, andnonwoven webs including spunbond webs, meltblown webs, carded fiberwebs, air laid webs, and the like, made from thermoplastic materialssuch as polyolefin (e.g. polyethylene and polypropylene homopolymers andcopolymers), polyesters, polyamines, and the like. Modifiednanoparticles can be coated on various types of fabric, film, or fibers.Modified nanoparticles can be coated in various amounts depending onneed. Suitably, modified nanoparticles are coated on fabrics, films, orfibers in an amount of about 0.001 to 10.0 grams per square meter andmore suitably about 0.1 grams per square meter.

In another embodiment of this invention, the modified nanoparticle areused to absorb gases that plants produce to ripen fruit. Ethylene gas isproduced by plants as a hormone to aid fruit ripening. By removingethylene gas as it is produced, fruit ripening can be slowed andcontrolled. Permanganate ion modified alumina nanoparticles are usefulin removing ethylene gas. In one embodiment the permanganate ionmodified alumina nanoparticles are adsorbed onto spunbond polypropylenefabric. The fabric has a negative streaming potential and the positivelycharged nanoparticles are held strongly onto the fiber surface. Thefabric can then be used in packaging and storing fruit such as bananasto inhibit ripening by removing ethylene gas. The fabric can be used towrap the fruit, as a bag to hold the fruit, or swatches can be includedin the current packaging. The modified nanoparticles can also be sprayedonto a box or other packaging material used in transportation andstorage of fruit. In one embodiment the cloth has a purple color due tothe permanganate ions, and when the fabric is saturated with ethylenethe fabric changes to a brown color. This color change acts as anindicator that the fabric needs replacement.

Modified nanoparticles of this invention are useful in removing odorouscompounds from solutions such as water and urine. The modifiednanoparticles could be applied to water treatment systems for use inremoving sulphurous compounds from well water or in toilet tanks toreduce the odors resulting from urine. The modified nanoparticles ofthis invention are so effective against removing offensive components inurine that the yellow color often present in urine is neutralized,leaving a clear liquid. The modified nanoparticles of this inventioncould also be used in liquid detergents and household cleaners to removeodors.

In one embodiment of this invention the modified nanoparticles areapplied to an absorbent article. The term “absorbent article” includeswithout limitation diapers, training pants, swim wear, absorbentunderpants, baby wipes, adult incontinence products, feminine hygieneproducts, absorbent tissues, medical garments, underpads, bandages,absorbent drapes, and medical wipes, as well as industrial work weargarments. In one embodiment the modified nanoparticles can be added tothe absorbent material of these products. In another embodiment themodified nanoparticles can be applied as a coating on any fabric or filmlayer, such as the inner liner or outer cover of a diaper. In oneembodiment the modified nanoparticles can be applied as a coating on abreathable film of an outer cover of an absorbent article such as adiaper or incontinence product to absorb odors. The modifiednanoparticles can also be applied to paper towels and wet wipes for usein cleaning odorous liquids. The absorbent articles absorb the odorousliquid and the modified nanoparticles bind the odorous compounds fromthe liquid neutralizing the smell.

In another embodiment of this invention, the nanoparticles are used asaerosol odor neutralizers/deodorants. The modified nanoparticles arepackaged with a propellant that allows spraying the modifiednanoparticles into the air for removal of gases and odorous compounds.The modified nanoparticles can be used in a household air freshener orbe used in combination with a mist emitted from a vaporizer orhumidifier.

The modified nanoparticles can be used in oral care. Sulphur and aminecompounds are often the reason for bad breath. Modified nanoparticlescan be added to oral care products such as mouth washes, oral-carechewing gums, toothpaste and/or toothbrush fibers. Using a silicananoparticle modified with copper ions would be one such modifiednanoparticle useful in oral care. Silica is widely used in toothpastesas an abrasive and the modified nanoparticles typically contain smalllevels of copper ions, far below levels in multiple vitamin tablets.Thus there should not be a health concerns with this use of the modifiednanoparticles.

The modified nanoparticles are also useful as a breath indicator.Modified nanoparticles can be used as a color indicator in the presenceof odorous compounds. In one embodiment of this invention a cellulosewipe coated with copper ion modified silica nanoparticles is placed in aplastic tube such as a straw. When the user breathes into the straw thecellulose wipe turns from green to blue indicating odors such as ammoniavapor or sulfur compounds. A color change can occur with even a lowamount of odorous compounds.

Example 1

A dilute suspension of modified silica nanoparticles was made by adding1 milliliter of SNOWTEX C®, available from Nissan Chemical Industries,Ltd., Houston, Tex., to 9 milliliters of deionized water. The suspensionwas pipetted in equal portions into four cuvets. Solutions of 0.01percent by weight of each of copper chloride (CuCl₂), silver nitrate(AgNO₃), and zinc chloride (ZnCl₂), all from Aldrich Chemical Company,Milwaukee, Wis., were prepared and one drop of each was added to aseparate cuvet. The Zeta Potential of all four suspension was thenmeasured by a Zetapals Unit, available from Brookhaven InstrumentsCorp., Holtsville, N.Y. The Zeta potential of the SNOWTEX C controlsuspension was measured to be −25 millivolts. The Zeta potential of boththe SNOWTEX C/copper chloride suspension and the SNOWTEX C/silvernitrate suspension were measured to be −11 millivolts. The Zetapotential of the SNOWTEX C/zinc chloride suspension was measured to be−8 millivolts. The difference in Zeta Potential between the solutionswas evidence that the metal ions had absorbed onto the silicananoparticle.

A furfuryl mercaptan solution was prepared for testing the odor removalproperties of the modified silica nanoparticles. A stock solution of0.001 percent by weight furfural mercaptan solution, available fromAldrich Chemical Co., Milwaukee, Wis., was made in distilled water. Thesolution had a strong odor. High performance liquid chromatography(HPLC) was used to measure concentration changes. A Zorbax EclipseXDB-C18, 4.6 by 150 millimeter, 5 micron column was used along with 100percent acetonitrile eluent. One microliter of the furfuryl mercaptansolution was injected into the HPLC column with a flow rate of 0.25milliliters/minute. FIG. 2A, the generated HPLC chromatogram, showsfurfuryl mercaptan peak to have an area of 16918 milliabsorptionunits·seconds (maus).

One drop of the SNOWTEX C/copper ion suspension was then added to 10milliliters of the furfuryl mercaptan solution. The furfuryl mercaptanodor rapidly disappeared and one microliter of this furfuryl mercaptansolution was injected into the HPLC column with a flow rate of 0.25milliliters/minute. FIG. 2B, the generated HPLC chromatogram, shows thefurfuryl mercaptan peak to have an area of 188 milliabsorptionunits·seconds (maus). The concentration of the furfuryl mercaptan wasgreatly reduced, and the detectable odor as well, with the addition ofthe modified nanoparticles.

Example 2

The SNOWTEX C/copper ion suspension was tested on human urine todetermine the effectiveness in odor reduction. HPLC, as described inExample 1, was used to measure the components of urine (obtained fromthe inventor). One drop of the SNOWTEX C/copper ion suspension fromExample 1 was tested against 0.1 gram of Purite Micronet MN-150 latexparticles, available from Purolite Company, Philadelphia, Pa., and 0.1gram of activated charcoal, available from Aldrich Chemical Co.,Milwaukee, Wis., Each of these were added to a separate 3 grains ofurine. The urine odor of the sample with the SNOWTEX C/copper ionsuspension was almost completely eliminated after 3-5 seconds, comparedto about 10 minutes for the activated charcoal. The latex particlesnever did remove the odor. FIG. 3A shows the HPLC chromatogram of theurine sample and FIG. 3B shows the chromatogram of the urine sampleafter the modified silica nanoparticles were added. Table 1 summarizedthe comparison of the HPLC peaks for the 4 samples. The modified silicananoparticles performed substantially better in removing the urinecomponents then the present commercial materials.

TABLE 1 Urine component HPLC peaks (peak retention time (minutes)) areaof area of area of area of area of area of peak at peak at peak at peakat peak at peak at Sample 3.87 min. 4.04 min. 4.77 min. 5.64 min. 5.88min. 6.23 min. Urine 924 maus 345 maus 50 maus 17 maus 829 maus 228 mausUrine + Modified 0 0 12 maus 0 701 maus  2 maus Silica NanoparticlesUrine + Purite Latex 773 maus 300 maus 0 17 maus 820 maus 156 mausParticles Urine + Activated 900 maus 0 50 maus 17 maus 820 maus  10 mausCharcoal

Example 3

The odor removal properties of a modified nanoparticle when dry andcoated on a surface was tested by coating a 10.16 centimeter squareone-ply HI-COUNT® paper towel, available from Kimberly-ClarkCorporation, Neenah, Wis., with the SNOWTEX C/copper ion suspension ofExample 1 further diluted by 50 percent. The paper towel was coated bydipping the paper towel sample into the suspension. The wet paper towelwas air-dried on a sheet of glass. The dried towel was placed over themouth of a 100 milliliter beaker and held by a rubber band. The beakercontained 20 milliliter of the 0.001 percent by weight furfurylmercaptan solution. A second untreated control HI-COUNT® paper towel wasplaced over an identical beaker as a control. The odors from thefurfuryl mercaptans penetrated the untreated paper towel. However, noodors penetrated the paper towel treated with the modified nanoparticlesfor about three hours. After three hours the modified nanoparticles weresaturated and the odors were detectable. The treated paper toweldeveloped a dark area over the beaker during testing resulting from thebinding of the furfuryl mercaptans.

Example 4

The odor removing properties of modified nanoparticles as an invisiblecoating on a bathroom tile was tested by treating a standard bathroomtile (15 centimeter×15 centimeter) from Home Depot with copper modifiedsilica nanoparticles of Sample 1. The suspension of copper modifiedsilica nanoparticles was applied to a KIM-WIPE®. The moist KIM-WIPE® wasused to wipe the bathroom tile surface and a second dry KIM-WIPE® wasused to wipe off any excess liquid. 3.6 microliters of ammonia, 28percent ammonia in water, available from Aldrich Chemical Co.,Milwaukee, Wis., was introduced to a laboratory desiccator via syringeand after 10 minutes an aliquot of the air/odor was sampled and analyzedto determine the concentration of ammonia in the desiccator. Theexperiment was repeated three times; once with no tile in thedesiccator, once with an untreated control tile in the desiccator, andonce with the modified nanoparticle treated tile in the desiccator. Theammonia gas was measured by use of a Drager tube, available from SKC,Inc., Pennsylvania, which could measure ammonia in air concentrationsfrom 2 to 30 parts per million. A volume of 60 milliliters of theair/odor was pulled out of the desiccator by means of a syringe. TheDrager tube was connected by Tygon tubing between the desiccator and thesyringe. The ammonia concentration in the desiccator was measured at 20parts per million with no tile and with the untreated tile. The ammoniaconcentration in the desiccator with the modified nanoparticle treatedtile was measured at less than 2 parts per million. The modifiednanoparticles on the standard bathroom tile were effective insubstantially reducing ammonia gas and odor.

Example 5

The following experiment was performed to demonstrate the use ofmodified nanoparticles of this invention in extending the shelf life offruit. Permanganate modified alumina nanoparticles were adsorbed onto a5.0 centimeter by 5.0 centimeter piece of 2 ounce spunbond polypropylenefabric at a level of 0.01 percent modified nanoparticle weight/fabricweight. The amount of permanganate ion was approximately 0.0001 percention weight/nanoparticle weight, monitored by measuring the change innanoparticle Zeta Potential. Each of three yellow bananas with no brownspots from the same bunch were placed into an airtight bag. In the firstairtight bag the modified nanoparticle treated fabric was placed. In thesecond bag contained an untreated 5.0 centimeter square spunbondpolypropylene fabric as a control. The third bag contained no fabricpiece also as a control. The three airtight bags were stored at ambienttemperature for four weeks. At the end of four weeks the bananas in thetwo control bags were completely black, soft to the touch, and oozingliquid. The banana in the bag with the modified nanoparticle treatedfabric was firm to the touch and had only a few brown markings. Thisdemonstrated that the ripening process was slowed by the modifiednanoparticles.

Example 6

To demonstrate the odor removing properties of modified organicnanoparticle of this invention copper ions were adsorbed ontopolystyrene nanoparticles. A dilute suspension of modified polystyrenenanoparticles was made by adding 1.0 milliliter of polystyrenenanoparticle suspension, the nanoparticles having a particle diameter of64 nanometers, available from Polysciences, Inc., Warrington, Pa., to9.0 milliliters of deionized water. The polystyrene nanoparticlesuspension had a Zeta Potential of −49 millivolts, as measured by theZetapals Unit as in Example 1. Two drops of 0.01 percent by weightcopper chloride (CuCl₂) solution was added to the polystyrenenanoparticle suspension. After the addition of the 2 drops of copperchloride solution the Zeta Potential of the polystyrene solution wasmeasured at −16 millivolts, thus confirming copper ion adsorption ontothe polystyrene nanoparticles. One drop of the modified nanoparticlesolution was added to a 2.0 milliliters of 0.001 percent by weightsolution of furfuryl mercaptan. High performance liquid chromatographyas described in Example 1 was used to measure furfuryl mercaptanpresence before and after adding the modified nanoparticles. The area ofthe furfuryl mercaptan peak before the addition of the modifiednanoparticles was 193 milliabsorption units and after the addition ofthe modified nanoparticles was 14 milliabsorption units. The coppermodified polystyrene nanoparticles are useful in removing sulphurouscompounds.

Example 7

A dilute suspension of modified silica nanoparticles was made by adding1 milliliter of SNOWTEX CO, available from Nissan Chemical Industries,Ltd., Houston, Tex., to 9 milliliters of deionized water. The suspensionwas pipetted in equal portions into three different cuvets. Solutions of0.01 percent by weight of each of copper chloride (CuCl₂), iron (II)chloride (FeCl₂), and iron (III) chloride (FeCl₃), all from AldrichChemical Company, Milwaukee, Wis., were prepared and one drop of eachwas added to a separate cuvet. The Zeta Potential of all threesuspensions was then measured by a Zetapals Unit. The Zeta potential ofthe SNOWTEX C® control suspension was measured to be −22 millivolts. TheZeta potential of the SNOWTEX C/copper chloride suspension was measuredat −10 millivolts, the SNOWTEX C/iron(II) chloride suspension at −13millivolts, and the SNOWTEX C/iron (III) chloride suspension at +13millivolts. One drop of each of the modified nanoparticle solutions wasadded to a separate 2.0 milliliter solution of 0.001 percent by weightfurfuryl mercaptan. High performance liquid chromatography as describedin Example 1 was used to measure furfuryl mercaptan presence before andafter adding the different modified nanoparticles. The results aresummarized in Table 2. Each of the modified nanoparticles weresuccessful in removing furfural mercaptan from the solution.Additionally, iron (III) ion modified silica nanoparticles had apositive Zeta Potential which can allow application to fabrics made frommaterials such as polypropylene, polyethylene, nylon, and cotton, whichhave negative value streaming potentials.

TABLE 2 Area of furfuryl Percent of odor Sample Zeta Potential mercaptanpeak removed SNOWTEX C/Cu⁺² −10 3.2 maus 97% SNOWTEX C/Fe⁺² −13  38 maus67% SNOWTEX C/Fe⁺³ +13 3.4 maus 97%

While the embodiments of the invention described herein are presentlypreferred, various modifications and improvements can be made withoutdeparting from the spirit and scope of the invention. The scope of theinvention is indicated by the appended claims, and all changes that fallwithin the meaning and range of equivalents are intended to be embracedtherein.

I claim:
 1. An article of manufacture, comprising: a composition forremoval of gaseous or odorous compounds comprising a first modifiednanoparticle, the first modified nanoparticle including a firstnanoparticle comprising a first positive Zeta Potential, the firstnanoparticle further comprising alumina, magnesium oxide, orcombinations thereof, a diameter of less than 500 nanometers, and asurface area of at least about 200 square meters/gram, the firstmodified nanoparticle further including at least one negatively chargedmetal ion complex adsorbed onto the first nanoparticle, the at least onenegatively charged metal ion complex selected from the group consistingof permanganate ion, wherein the composition further comprises a secondmodified nanoparticle, the second modified nanoparticle including asecond nanoparticle comprising a negative Zeta Potential and at leastone positively charged metal ion adsorbed onto the second nanoparticle,wherein the first modified nanoparticle is capable of binding a firstgaseous or odorous compound and the second modified nanoparticle iscapable of binding a second gaseous compound, wherein the article ofmanufacture changes color as the article of manufacture becomessaturated with gaseous or odorous compounds.
 2. The article ofmanufacture of claim 1, wherein the second modified nanoparticleincludes a second nanoparticle comprising silica, titanium dioxide,gold, zinc oxide, polystyrene, and combinations thereof; and wherein theat least one positively charged metal ion comprises a metal ion selectedfrom the group consisting of copper ion, silver ion, gold ion, iron ion,and combinations thereof.
 3. The article of manufacture of claim 1,wherein the first nanoparticle further comprises a second lower positiveZeta Potential after adsorption of the at least one metal ion or metalion complex onto the first nanoparticle.
 4. The article of manufactureof claim 1, wherein the first nanoparticle comprises a surface area ofat least about 500 square meters/gram.
 5. The article of manufacture ofclaim 1, wherein the at least one gaseous compound comprises a compoundselected from the group consisting of ethylene gas, carvone, terpenoids,and combinations thereof.
 6. The article of manufacture of claim 3,wherein the second lower positive Zeta Potential is determined by anadd-on amount of adsorbed metal ions.
 7. The article of manufacture ofclaim 1, wherein the first nanoparticle comprises a first positive ZetaPotential of about 1 to 70 millivolts.
 8. The article of manufacture ofclaim 1, wherein the second nanoparticle comprises a negative ZetaPotential of about −1 to −50 millivolts.
 9. The article of manufactureof claim 1, wherein the modified nanoparticle is adsorbed onto thearticle of manufacture by an electric potential difference between themodified nanoparticle and the article of manufacture.
 10. The article ofmanufacture of claim 1, wherein the article of manufacture comprises anabsorbent article.
 11. The article of manufacture of claim 10, whereinthe absorbent article comprises a diaper.
 12. The article of manufactureof claim 10, wherein the absorbent article comprises a feminine hygieneproduct.
 13. The article of manufacture of claim 1, wherein the articleof manufacture comprises a paper towel.
 14. The article of manufactureof claim 1, wherein the article of manufacture comprises a household airfreshener.
 15. The article of manufacture of claim 1, wherein thearticle of manufacture comprises an oral hygiene product.
 16. Thearticle of manufacture of claim 1, wherein the article of manufacturecomprises a wipe.
 17. The article of manufacture of claim 1, wherein thearticle of manufacture comprises a fibrous cloth.
 18. The article ofmanufacture of claim 1, wherein the article of manufacture comprises anair filter.
 19. The article of manufacture of claim 1, wherein thearticle of manufacture comprises an odor adsorbing powder.